By Vvon Engineering Team | Published | Updated
Assess spinning, weaving and dyeing demand, seasonal exports, roof condition and site-specific financial returns.
Solar EPC & street lighting RFQ checklist (TXT)
For a textile mill, compare rooftop solar with efficiency and other energy investments using the actual process load. PV can reduce purchased daytime energy; it does not supply a night shift physically without other generation or storage.
Large roofs and recurring daytime loads can make a mill suitable for solar. The feasible size and share of consumption depend on the measured demand, usable roof and approved connection.
Measure spinning, weaving, dyeing and finishing separately where possible. Moving a batch can affect labour, heat supply, water, delivery and quality, so include those implications before assigning a load-shifting saving.
| Input | Evidence needed | Why it matters |
|---|---|---|
| Consumption | Twelve months of bills and representative interval demand | Separates direct use, exports and changing demand. |
| Generation | Location, layout, weather dataset and loss assumptions | Estimates output month by month. |
| Connection | Sanctioned load, transformer and utility requirements | Establishes eligible capacity and approval conditions. |
| Installed cost | Dated itemised quotation and exclusions | Includes roof work, connection and commissioning. |
| Operating cost | Maintenance, insurance and replacement assumptions | Avoids treating later electricity as cost-free. |
Use a site-specific monthly generation estimate. Check the current AC/DC capacity and transformer conditions with the utility, then value direct consumption and export through the actual tariff and agreement.
Published projects can demonstrate installation scale, but their capacities alone do not establish payback. Ask for operating and financial evidence before treating a reference as a comparable return.
| Model component | Required evidence |
|---|---|
| Installed cost | Dated scope and exclusions. |
| Generation | Resource dataset, layout and loss assumptions. |
| Value | Measured self-consumption, tariff and export-credit treatment. |
| Ongoing cost | Maintenance, insurance, repair and replacement. |
| Return | Annual cash flow and sensitivity, with discount and finance assumptions. |
Compare offers using the same generation, demand, tariff and cost assumptions. A lower quoted payback may reflect optimistic inputs rather than a better project.
Assess the exact sheet profile, fixing system and full structure. Approved standing-seam clamps may avoid penetrations, but ordinary corrugated sheets cannot be assumed to use them. RCC roofs also need capacity and wind checks plus a compatible waterproofing detail.
Then there is what the process does to the roof environment. A dyeing house vents steam and chemical-laden vapour, and modules and mounting hardware downwind of those vents corrode faster than the same equipment on a spinning shed. Lint from blowroom and carding exhausts settles on glass and mats when it gets wet. Neither problem stops a project, but both belong in the array layout and in the cleaning schedule, and both are easier to design around before the plant is built than to explain afterwards.
A textile mill is an electrically noisy site. Variable frequency drives on ring frames, looms and pumps, plus the capacitor banks fitted for power factor correction, can produce enough harmonic distortion at the main board to cause inverters to trip repeatedly. The failure mode is unpleasant because it is intermittent: the plant works during commissioning and then starts dropping out under a particular combination of running machines weeks later.
This one catches mill owners out, and it is worth being blunt about it before contract rather than after. A standard grid-tied net-metering plant shuts down when the grid fails. It has to: the anti-islanding protection that stops the inverters energising a dead network is a condition of the utility approval, and it protects the linemen working on the line. An ordinary grid-following plant will not keep the mill energised during load-shedding unless something else has been designed in.
If outage cover is what you actually want, that is a different architecture and a different budget: a hybrid system with storage, with a defined critical-load schedule listing which machines are held up and for how long. On a spinning or weaving floor that schedule is usually short, because carrying production machinery through an outage is rarely economic, while holding the control systems, humidification and the safety and lighting circuits often is. Decide which of the two you are buying at the specification stage. A quotation for a grid-tied plant is not a quotation for backup, and the two are frequently conflated in tender documents.
Two documents cause most of the delay at step three. The structural certificate has to be signed by a qualified engineer, and the module and inverter datasheets have to carry their IEC certification numbers. Applications also come back when the SLD omits the AC and DC surge protection devices and the earthing arrangement, or when the proposed inverter is not on the utility's approved list. All four are avoidable before submission.
Agree who carries out each survey, structural and electrical design, procurement, installation, utility submission and maintenance task. Request verifiable references and the proposed handover documents.
Consult the relevant edition and the documents for the exact equipment and site: SREDA: Net Metering Guidelines and current application documents; IEA PVPS: operation and maintenance in different climates; JinkoSolar: model datasheets, certificates, installation manuals and warranties; IEC 62548-1: PV array design requirements.
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